Hydraulic system



July 18, 1950 E. Y. SEBORG 2,515,531

HYDRAULIC SYSTEM Filed Jan. 10, 1947 3 Sheets-Sheet l Fig.1 fr

6L rnest' Seborg (JQTTORNEYJ y 8, 1950 E. Y.-SEBORG 2,515,531

HYDRAULIC SYSTEM Filed Jan. 10, 1947 3 Sheets-Sheet 3 Figs 52 50 k 9 Wk v Gdvnest 2 mm;

6 dark 5 '62 29 CATTOQNEW Patented July 18, 1950 UNITED STATES HYDRAULIC SYSTEM Earnest Y. Seborg, Rockford, Ill., assignor to Barnes Drill 00., Rockford, 11]., a corporation of Illinois Application January 10, 1947, Serial No. 721,353

6 Claims. 1

The invention relates to hydraulic systems for machine tools or other machines having reciprocatory machine elements.

One object of the invention is to provide an improved hydraulic system of the above general character having means for insuring quick, yet

shockless stopping of the machine element, and for introducing a delay or dwell in the return movement of the element.

A more specific object is to provide a dwell mechanism for use in hydraulic systems of the type used in machine tools which is rendered operative solely in response to a reversal of fluid flow in a part of the system as the machine element reaches one end of its reciprocatory stroke, thus avoiding the use of separate actuating means for rendering the dwell mechanism effective and automatically insuring proper coordination of that mechanism with the reversing mechanism of the system and producing a simple,

practical control which is efiicient and reliable.

in operation.

Other objects and advantages of the invention will become apparent from the following detailed description of the preferred embodiment illustrated in the accompanying drawings, in which:

Figure 1 is a diagrammatic view of a hydraulic system embodying the features of the invention, showing the system applied to a vertical type honing machine.

Fig. 2 is a diagrammatic view similar to Fig. 1, showing the position of the parts as the direction of movement of the reciprocatory element of the machine is reversed.

Fig. 3 is a diagrammatic view showing the hydraulic system as applied to a horizontal honing machine.

Fig. 4 is a sectional view taken in a vertical plane substantially on the line 4-4 of Fig. 3.

Fig. 5 is a sectional view taken in a horizontal plane substantially on the line 5-5 of Fig. 3.

While the invention is susceptible of various modifications and alternative constructions, I

I have shown in the drawings and will herein deor conduits are connected alternately to a source of pressure fluid to determine the direction movement of a reciprocating machine element and in which the pressure of the fluid medium in the system is controlled by a hydraulically balanced relief and by-pass valve. The conduits may lead directly to the actuator which reciprocates the machine element or to an auxiliary control device which controls such reversal. Valves of the type referred to are commonly arranged so as to by-pass the pressure fluid from the main pressure supply line when unbalanced, and such unbalancing is most conveniently effected by venting one end of the valve chamber.

The invention provides novel means for venting such relief valves automatically as an incident to the reversal of the pressure fluid connection in the system and for maintaining the valve in an unbalanced condition for a predetermined adjustable interval. This insures quick, yet shockless stopping of the machine element at go the end of its reciprocatory stroke and delays the start of the return stroke for that predetermined interval. The operation of the venting means is thus automatically coordinated with the operation of the other elements of the sys- 25 tem at all times without requiring resetting or other adjustment when the stroke of the machine element is changed. Provision is made whereby the venting means may be cut into and out of service at will without affecting the other operations of the system and whereby it may be adjusted to provide a dwell of any desired length.

For purposes of illustration, the improved hydraulic system has been shown in the form particularly suitable for honing machines which operate to rotate and simultaneously reciprocate an abrasive tool III in a cylindrical bore ll formed in a workpiece l2. In the exemplary machine shown in Figs. 1 and 2. the tool is carried by a rotatably driven driver [3 Journaled in a head ll supported and guided for movement in a vertical plane by upright guide rods l5.

Reciprocation of the head I is effected by a pressure fluid operated actuator or servomotor herein shown as comprising a piston 2| working in a cylinder 22. The cylinder is stationarily supported in a vertical position on the machine frame above the head 14 and the piston 2| is operatively connected with the head by a piston rod 23.

Pressure fluid is supplied to the actuator 20 by a continuously driven pump P through a main supply line and under control of a direction valve V. In the particular machine shown, pressure is maintained on the rod end of the piston 55 during its movement in both directions by means haust line 23, according to the position of the valve member.

When pressure fluid is admitted to both ends of the cylinder 22, as when the valve member is in the position shown in Fig. 1, the piston 2| is forced downwardly due to the smaller effective area presented by its lower or rod end. In such movement of the piston the fluid from the lower end of cylinder is discharged through the branch line 25 and returned to .the main supply line 25. Upon connection of the conduit 21 to the drain 23, the piston 2| is forced upwardly by the pressure exerted on its lower face. In this movement the fluid from the upper end of the cylinder -cylinder 22 when the machine is idle.

In accordance with the usual practice. the operation of the direction valve V is controlled by the movements of the head |4 through the medium of a pilot or distributor valve V--| This valve, as herein shown, is of the four-way rotary type and is adapted to be rocked between two limit positions by an actuator shaft 3|, which in turn is rocked about its axis by an actuator disk 32 operatively connected with the head H by an endless flexible connecting member 33. Pressure fluid supplied to thetpilot valve through an auxiliary supply line 34 is directed alternately to opposite ends of the direction valve V by way of conduits 35 and 36, the non-pressure end of the valve being connected to the drain 29 in each case. The arrangement is such that when the pilot valve V| is set in the position shown in Fig. 1, pressure fluid is delivered through the conduit 35 to shift the valve member 28 of the direction valve to its left-hand position in which it directs pressure fluid to the upper end of the actuator cylinder 22 to drive the piston 2| and head |4 downwardly.

When the pilot valve is operated to its alte'rnate position, as shown in Fig. 2, pressure fluid delivered through the conduit 36 shifts the valve member 28 to its right-hand position in which it connects the upper end of the actuator cylinder 22 to the drain 23 to effect an upward movement of the piston 2| and head i4. i

The volume of fluid delivered to the main supply line and consequently the rate of movement of the head is regulated by a metering valve V2 interposed in the supply line 25 while the pressure of the fluid is controlled by a hydraulically balanced valve V3, which serves additionally to by-pass the supply of fluid to the sump during idle periods of the machine. The valve V3 as shown -is 01' the conventional type having a chamber 33 receiving fluid from the pump P and discharging it into the main supply line 25 ahead of the metering valve V-2. The chamber 33 also has an outlet port 40 through which fluid may be by-passed to the sump R. Flow of fluid through the outlet port is controlled by a movable valve member 4| which has a piston 75 V6.

enlargement 42 at its upper end. A passage 46 in the valve casing, connected'to the supply line 25, bleeds a small amount of fluid therefrom to the chamber above the piston 42, whereby sumcient pressure is maintained on the piston to obtain the necessary working pressure in the hydraulic system. A spring 44 acting on the valve member assists in shifting the member to its partially closed position and insures the maintenance of suflicient back pressure in the system at all times for performance of the, various control functions.

Opening from the upper end of the valve chamber 33 is a vent line 46 by which the pressure on the upper face of the valve piston 42 may be relieved to initiate-movement of the valve member to the open position. To enable the valve to regulate the maximum pressure of the fluid in the system, the vent line is provided with a relief valve V4, herein shown as a conventional spring-biased valve, which may be set to open at any predetermined pressure. The vent line may also be opened to stop the machine by means of a stop valve V5 arranged for operation by a solenoid 41 under control of a stop switch 8.

In accordance with the invention, the improved dwell mechanism is connected in the system to provide for automatically opening the vent line 46 as an incident to the reversal of the supply of pressure fluid to the direction valve V and to maintain the vent line open for a predetermined adiustableinterval so as to introduce a time delay or dwell in the return movement of the head i4. For this purpose the vent line 46 is connected with a branch line 43 leading to the drain 2! and having a normally closed valve V6 and a normally open valve V-1 arranged therein in series. The valve V6 is provided with a cylinder and piston actuator 46 connected by a conduit 56 with the conduit 35 leading to the right end of the direction valve V. The arrangement is such that when the conduit 35 is connected to the auxiliary supply line 34, the valve V5 closes the branch line 43, thus allowing pressure to build up in the chamber of the valve V-3 and causing the latter valve to close the by-pass port. When the pilot valve Vl is Operated to its reverse position, the conduit 35 is connected to the drain 23, thus relieving the pressure on the valve actuator 43 and permitting the valve V6 to open and vent the valve V3 to cause the latter to open. Pressure fluid supplied by the pump P is thus by-passed to the sump R and the reciprocation of the head I4 is interrupted.

The by-passing of the fluid is continued until the vent is closed by operation of the valve V1. As herein shown, this valve comprises a plunger 5| working in a chamber 52 and normally urged by a spring 53 to the open position shown in Fig. 1 in which it leaves unobstructed the inlet and outlet ports to which the two sections of the branch line 48 are connected. The end of the valve chamber 52 opposite the spring 53 is connected by a conduit 54 with the conduit 36 leading to the left end of the direction valve. Accordingly, upon reversal of the pilot valve at the lower end of the reciprocatory stroke of the head l4, fluid at the reduced pressure determined by the setting of the valveV-I is supplied to the valve chamber by way of the conduits 34, 36 and 54. The valve plunger 5| is thereby shifted to the left against the action of the spring 53 to close the branch line 48 and thus terminate the venting of the valve V3 initiated by the opening of the valve Since the conduit 36 is connected to the drain 29 when the conduit 36 is connected '0 the auxiliary supply line 34, the valves V6 and V-l will both open for an interval, thus venting the valve V-3 and causing it to by-pass the supply of fluid to the sump. Reciprocation of the head is therefore interrupted automatically as an incident to the reversal of the fluid supply to the direction valve. The open interval and thus the length of the dwell in the reciprocation of the head I4 is determined by the time required for the plunger 5| to move to closed position under the action of the fluid supplied thereto, suillcient pressure be-' ing maintained in the system for that purpose by the spring 44 of the valve V3 as heretofore explained. To permit of varying the dwell, a metering valve V-8 is interposed in the conduit 54 for regulating the rate at which fluid is admitted to the chamber 52.

With the valves V-6 and V-1 connected in the system as above described, it will be apparent that the dwell in movement of the head I4 is V-Ill. For this purpose the' member is formed with a tapering peripheral groove 66 for metering purposes and with a transverse notch Ill prointroduced at the lower end of its reciprocatory stroke. To insure quick return of the valve V--| upon reversal of the pilot valve V-l at the other end of the stroke, the chamber 52 is provided with an exhaust line 55 arranged in by-passing relation to the metering valve V-8. A check valve V--9 in the exhaust line prevents passage of fluid into the valve V--"|.

Fig. 3 shows the improved hydraulic system as applied to a machine tool, as, for example, a horizontal honing machine in which the reciprocatory machine element is driven through suitable gearing G by a reversible rotary hydraulic motor M, instead of by a cylinder and piston actuator. In this case, two conduits 60 and 6| extend from the direction valve V to the motor M and are alternately connected to thevsupply line and the drain 29 to determine the direction of rotation of the motor. A stop valve V-ll of any preferred type is interposed in the drain line 29 in place of the foot valve to prevent the system from draining when the machine is idle. As in the previously described system, the valves controlling automatic venting of the relief valve V-3 are operatively connected with the conduits and 36 leading from the pilot valve V--l to the direction valve V. In this instance, a passage 43 in the valve piston 42 bleeds a small amount of fluid under pressure into the chamber above the valve piston to balance the same, the operation being otherwise the same as heretofore described.

The valves and the other elements forming the dwell mechanism of the system may be conveniently incorporated in a unitary structure, thus reducing their cost and materially facilitating installation in existing machines. In its preferred form shown in Figs. 3-5, the dwell mechanism unit comprises an elongated casing 62 having parallel longitudinal bores, one forming the chamber 52 for the valve member SI and the other forming a stepped chamber for the valve V6. The casing is closed at one end by a panel 63 which is preferably dimensioned to project at opposite sides of the valve casing and thus provide a flange for mounting the unit on the machine. The other end of the casing is closed by a head 64 having a stepped bore 65 forming the valve chamber of the check valve V6 and a parallel bore 66 forming the cylinder of the valve actuator 49. Suitable cored or drilled passages in the casing interconnect the various valve chambers as heretofore explained.

Also extending longitudinally of the casing at vidlng a passage connecting the two sections of the vent line 48. The groove 69 and slot 10 are preferably positioned so that the passage through the metering valve V-8 is closed when the valve V-lll is set to close the vent line 48, thus preventing unnecessary shifting of the valve member 5| when the dwell mechanism is' idle. At its forward end the valve member 68 is arranged to project through the panel 63 and is provided with a suitable operating element such as a knob II by which it may be rotated manually to set the valves V-B and V-Ill. 4

It will be apparent from the foregoing that the invention provides a hydraulic system of novel and advantageous character for machine tools or other machines having reciprocatory machine elements. With the improved system, quick and substantially shockless stopping of the element at the ends of its reciprocatory stroke is insured and a delay or dwell in the return movement of the element may be introduced at one end of the stroke. Operation of the dwell mechanism is effected solely as an incident -to the reversal of fluid flow in a selected part of the system, thus making the use of separate controls unnecessary and automotically coordinating the dwell mechanism with a reversing mechanism of the system. The dwell mechanism may be readily incorporated in a compact unitary structure which is simple to manufacture and which greatly facilitates the installation of such mechanism in existing machines.

I claim as my invention:

1. A hydraulic system having, in combination, a supply line, a pump adapted to be driven continuously, a relief valve receiving pressure fluid from said pump and having a vent line adapted when closed to cause fluid from said pump to be delivered to said supply line and when opened to interrupt such flow, a fluid operated control valve associated with said supply line, a distributor valve having a movable member, an inlet continuously-supplied with pressure fluid by said pump independently of said supply line and two outlets through which pressure fluid is delivered respectively .to correspondingly set said control valve when the movable valve member is shifted between opposite positions, a servomotor having a driven element moved in one direction when said control valve is set in one position with the vent line closed and in the other direction when the control valve is set in its other position with said vent line closed, a branch line connected to said vent line, a third valve controlling the flow of fluid out of said branch vent line and held closed when pressure fluid is supplied to one of said outlets, and a fourth valve in said branch vent line normally open to permit the flow of fluid therethrough when said third valve is open,

said fourth valve being responsive to the flow of a pressure fluid through said other outlet to interrupt the flow of fluid through said branch vent line after the lapse of a time interval.

2. A hydraulic system having, in combination, means providing a source of fluid under pressure, a distributor valve having two fluid pressure outlets and a member movable to direct fluid from said source to one or the other of said outlets, a

vent line, a supply line ior delivering pressure fluid from said source when said vent line is,

adapted when energized to maintain one of said vent valves closed, the other of said vent valves comprising a, plunger spring urged into a position opening said vent line and adapted to close the line after a predetermined movement, a chamber enclosing said plunger and adapted to receive pressure fluid to move the plunger in the valve-closing direction, and means for metering the flow of fluid from said other distributor valve outlet into said chamber.

3. A hydraulic system having, in combination, means providing a source of fluid under pressure, a distributor valve having two fluid pressure outlets and a member movable to direct fluid from said source to one or the other oi! said outlets, a vent line, a supply line for delivering pressure fluid from said source when said vent line is 'closed, two valves arranged in series relation to control the flow of fluid through said vent line, a fluid pressure actuator energized in response to a pressure build up in one of said outlets and adapted when energized to maintain one of the vent valves closed, means normally holding said other vent valve open, said other vent valve operating in response to fluid flow upon a pressure build up in said other outlet to close the vent line after the lapse of a predetermined interval, and selectively adjustable means for varying the rate of fluid flow from said other outlet to said other vent valve to determine the length of said interval.

4. A hydraulic system having, in combination, a source of fluid under pressure, a supply line from said source, a distributor valve operable to direct'the fluid from said supply line into either of two conduits selectively, a by-pass line communicating with said supply line, a control valve in said by-pass line adapted when open to by-pass the fluid from said suply line to a sump and when closed to prevent the passage of fluid through the by-pass line, an actuator for said valve connected to receive fluid under pressure from said source and operative when under pressure for maintaining the valve in closed position, a vent for said actuator operative when open to relieve the pressure therein and permit the valve to open, a pair of auxiliary valves for controlling said vent, pressure fluid connections from the respective auxiliary valves to said two conduits, and a metering valve in one of said connections for regulating the flow of pressure fluid therethrough to vary the time required for the associated valve to close after the introduction or pressure fluid into the connected conduit.

5. A hydraulic system having, in combination, a source of fluid under pressure, a supply line from said source, a distributor valve operable to direct the fluid from said supply line into either or two conduits selectively, a by-pass line communicating with said supply line, a control valve in said by-pass line adapted when closed or partially closed to maintain a predetermined flow of fluid in said supply line and when fully opened to by-pass excess fluid to a sump, an actuator for said valve connected to receive fluid under pressure from said source and operative when under pressure for maintaining said valve in closed or partially closed position, a vent line for said actuator operative when open to relieve the pressure therein and permit said control valve to open fully, a pair of valves interposed in said vent line, one of said valves being pressure fluid operated to close the vent line, a connection from one of said conduits to said one valve for supplying pressure fluid to shift the valve to closed position, a metering valve for regulating the flow of pressure fluid through said connection to vary the time required for the valve to close follow-. ing the introduction of pressure fluid into said one conduit, and a member common to said other valve of the pair and said metering valve operable manually to close said vent line and simultaneously shut off the flow oi. pressure fluid to said one valve.

6. A hydraulic system having, in combination, a source of fluid under pressure, a supply line leading from said source, a distributor valve operable to direct the fluid from said supply line to either of two conduits selectively, a control valve for said supply line having a vent line effective when closed to maintain the flow of pressure fluid in said supply line and when opened to interrupt such flow, a pair of independently operable vent controlling valves each operative when supplied with fluid under pressure to close the vent line, pressure fluid lines connecting said two conduits to the respective vent valves, and

'means for controlling the rate of fluid flow through one of said pressure fluid lines to regulate the time required for the associated vent valve to close.

. EARNEST Y. SEBORG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,510,205 Beaty Sept. 30, 1924 2,047,832 Morton July 14, 1936 

